Vacuum cleaner utilizing electrostatic filtration and electrostatic precipitator for use therein

ABSTRACT

An apparatus for filtering a dirty air stream in a vacuum cleaner to obtain a clean air stream includes subjecting the dirty air stream to a first cyclonic separation stage to obtain a partially cleaned air stream and subjecting the partially cleaned air stream to an electronic filtration stage and optionally a second cyclonic separation stage to obtain the clean air stream. The electronic filtration stage is optionally removable with a cyclonic cleaning stage from the vacuum cleaner. The electronic filtration stage is optionally an electrostatic precipitator which utilizes air flow through the vacuum cleaner to generate the voltage used by the electrostatic precipitator.

This application is a continuation-in-part of U.S. application Ser. No.09/227,712 filed on Jan. 8, 1999 and now U.S. Pat. No. 6,238,451.

FIELD OF THE INVENTION

This invention relates to vacuum cleaners which have a cyclonicseparation apparatus. In another aspect, the invention relates to anelectrostatic precipitator.

BACKGROUND OF THE INVENTION

Cyclone separators, which are sometimes referred to merely as cyclones,are devices that utilize centrifugal forces and low pressure caused byspinning motion to separate materials of differing density, size andshape. FIG. 1 illustrates the operating principles in a typical cycloneseparator (designated by reference numeral 10 in FIG. 1). The followingis a description of the operating principles of cyclone separator 10 interms of its application to removing entrained particles from an airstream in a vacuum cleaner.

Cyclone separator 10 has an inlet pipe 12 and a main body comprisingupper cylindrical portion 14 and lower frusto-conical portion 16. Theparticle laden air stream is injected through inlet pipe 12 which ispositioned tangentially to upper cylindrical portion 14. The shape ofupper cylindrical portion 14 and frusto-conical portion 16 induces theair stream to spin creating a vortex. Larger or more dense particles areforced outwards to the walls of cyclone separator 10 where the drag ofthe spinning air as well as the force of gravity causes them to falldown the walls into an outlet or collector 18. The lighter or less denseparticles, as well as the air medium itself, reverses course atapproximately collector G and pass outwardly through the low pressurecentre of separator 10 and exit separator 10 via air outlet 20 which ispositioned in the upper portion of upper cylindrical portion 14.

The separation process in cyclones generally requires a steady flow freeof fluctuations or short term variations in the flow rate. The inlet andoutlets of cyclone separators are typically operated open to theatmosphere so that there is no pressure difference between the two. Ifone of the outlets must be operated at a back pressure, both outletswould typically be kept at the same pressure.

When a cyclone separator is designed, the principal factors which aretypically considered are the efficiency of the cyclone separator inremoving particles of different diameters and the pressure dropassociated with the cyclone operation. The principle geometric factorswhich are used in designing a cyclone separator are the inlet height(A); the inlet width (B); the air outlet diameter (C); the outlet ductlength (D); the cone height (Lc); the dirt outlet diameter (G);and, thecylinder height (L).

The value d₅₀ represents the smallest diameter particle of which 50percent is removed by the cyclone. Current cyclones have a limitationthat the geometry controls the particle removal efficiency for a givenparticle diameter. The dimensions which may be varied to alter the d₅₀value are features (A)-(D), (G), (L) and (Lc) which are listed above.

Typically, there are four ways to increase the small particle removalefficiency of a cyclone. These are (1) reducing the cyclone diameter;(2) reducing the outlet diameter; (3) reducing the cone angle; and (4)increasing the body length. If it is acceptable to increase the pressuredrop, then an increase in the pressure drop will (1) increase theparticle capture efficiency; (2) increase the capacity and (3) decreasethe underflow to throughput ratio.

In terms of importance, it appears that the most important parameter isthe cyclone diameter. A smaller cyclone diameter implies a smaller d₅₀value by virtue of the higher cyclone speeds and the higher centrifugalforces which may be achieved. For two cyclones of the same diameter, thenext most important design parameter appears to be L/d, namely thelength of the cylindrical section 14 divided by the diameter of thecyclone and Lc/d, the length of the conical section 16 divided by thewidth of the cone. Varying L/d and Lc/d will affect the d₅₀ performanceof the separation process in the cyclone.

Due to its intended use, a vacuum cleaners is designed to filterparticles of varying sizes from an air stream. With most vacuum cleanerson the market, a filter material such as a paper bag is used to filterthe air. The bag will remove from the air stream any particle largerthan the size of the pore in the bag. Thus only a single stage offiltration may be employed. However, if a cyclone is used in a vacuumcleaner, then multiple filtration stages may be employed. This is due tothe fact that particle sizes which are generally to be filtered by avacuum cleaner take on a spectrum of values that necessitates that aplurality of cyclonic separators be used in a series. For example, thefirst cyclonic separator in a series may have a large d₅₀ specificationfollowed by one with a smaller d₅₀ specification.

For example, in U.S. Pat. No. 3,425,192, a vacuum cleaning assembly wasdisclosed which used a first frusto-conical cyclone and six secondarycyclones.

More recently, cyclonic technology has been improved and introducedcommercially into canister and upright vacuum cleaners. See for exampleU.S. Pat. No. 4,593,429. This patent discloses a vacuum cleaner designin which sequential cyclones are utilized as the filtration medium for avacuum cleaner. Pursuant to the teaching of this patent, the firstsequential cyclone is designed to be of a lower efficiency to removeonly the larger particles which are entrained in an air stream. Thesmaller particles remain entrained in the air stream and are transportedto the second sequential cyclone which is frusto-conical in shape. Thesecond sequential cyclone is designed to remove the smaller particleswhich are entrained in the air stream. If larger particles are carriedover into the second cyclone separator, then they will typically not beremoved by the cyclone separator but exit the frusto-conical cyclonewith the air stream.

One disadvantage of cyclonic vacuum cleaners is the amount of powerwhich is required to create an air flow sufficient to convey the dirtyair through the cyclones at sufficient speeds to maintain the airflowing cyclonically through the cyclones.

SUMMARY OF THE INVENTION

In order to achieve high levels of particle removal, cyclonic vacuumcleaners which are currently on the market incorporate a HEPA™ filter.Such filters are effective in removing small particulate matter from theair stream so that the air which exits the vacuum cleaner is essentiallyfor refiltered. One disadvantage of such HEPA™ filters is that theyprovide substantial resistance to the flow of air there through. Byremoving the HEPA™ filter, the pressure drop which occurs during thepassage of the air through the filter assembly of a vacuum cleaner maybe reduced by, eg., up to 20%. Accordingly, by removing the HEPA™filter, the flow rate through the vacuum cleaner may be substantiallyincreased and/or the size of the motor may be reduced by eg., up to 20%.However, the amount of particulate matter which will be contained in thedirty air stream will be increased.

The instant invention provides an alternate approach to the use of suchHEPA™ filters. Electrostatic filters generally provide minimalresistance to the flow of air and accordingly do not generally providemuch of the pressure drop as an air stream passes there through. Theelectrostatic filter may be designed to remove the same size particlesas are removed by the HEPA™ filter which is currently in use.Alternately, the electrostatic filter may be designed to remove evenlarger particles. Accordingly, by using an electrostatic filter, thepressure drops for a vacuum cleaner may be substantially reduced(compared to a vacuum cleaner using a HEPA™ filter). Further, theelectrostatic filter may provide enhanced particle remover compared toeven a HEPA™ filter and accordingly the clean air outlet from the vacuumcleaner may produce air which is even cleaner than that which isachieved from commercially available cyclonic vacuum cleaners which evenincorporate at HEPA™ filter.

In accordance with the instant invention, there is provided a vacuumcleaner comprising a dirty air inlet for receiving air containing dirt;a clean air outlet spaced for the dirty air inlet; an air flow pathextending downstream from the dirty air inlet to the clean air outlet;and, a filtration assembly positioned in the air flow path, thefiltration assembly comprising at least one cyclonic cleaning stage inflow communication with the dirty air inlet and having a partiallycleaned air outlet; and, at least one electrostatic precipitatorpositioned in the air flow path downstream from the at least onecyclonic cleaning stage and upstream of the clean air outlet.

In one embodiment, the at least one electrostatic precipitator comprisesa housing having at least one inlet and at least one outlet and at leastone member positioned therein, the at least one member movablypositioned in the housing for generating a high voltage potential inresponse to the movement of the at least one member in the housing and aconductive member for transmitting the high voltage potential to dirtentrained in the air.

In another embodiment, the at least one member is movable in response toair flow through the housing.

In another embodiment, the vacuum cleaner further comprises a batteryfor operating the vacuum cleaner and the at least one electrostaticprecipitator produces a high voltage potential in response to air flowthrough the electrostatic precipitator.

In another embodiment, the first cyclonic cleaning stage consists of onecyclone.

In another embodiment, the at least one cyclonic cleaning stagecomprises at least a first cyclonic cleaning stage and a second cycloniccleaning stage downstream from the first cyclonic cleaning stage. The atleast one electrostatic precipitator may be positioned in the air flowpath downstream from the first cyclonic cleaning stage and upstream ofthe second cyclonic cleaning stage. Alternately, the at least oneelectrostatic precipitator may be positioned in the air flow pathdownstream from the second cyclonic cleaning stage and upstream of theclean air outlet. The first cyclonic cleaning stage may comprise onecyclone and the second cyclonic cleaning stage may comprise from two tofive second cyclones. The second cyclonic cleaning stage preferablyremoves particulate material larger than that which is removed by the atleast one electrostatic precipitator.

In another embodiment, the at least one cyclonic cleaning stagecomprises a cyclone chamber removably mounted in a housing and the atleast one electrostatic precipitator comprises an electrostaticprecipitator removably mounted in the cyclone chamber. The cyclonechamber may have an air outlet and the electrostatic precipitator may bepositioned in the air outlet of the cyclone chamber. The cyclone chambermay have an air outlet and the electrostatic precipitator may beremovably mounted in the air outlet of the cyclone chamber.

In accordance with the instant invention, there is also provided avacuum cleaner comprising a dirty air inlet for receiving air containingdirt; a clean air outlet spaced for the dirty air inlet; an air flowpath extending downstream from the dirty air inlet to the clean airoutlet; and, a filtration assembly positioned in the air flow path, thefiltration assembly comprising a first cyclonic cleaning stage and asecond cyclonic cleaning stage downstream from the first cycloniccleaning stage; and, at least one electrostatic filter positioned in theair flow path downstream from the first cyclonic cleaning stage andupstream of the clean air outlet, wherein the second cyclonic cleaningstage removes particulate material larger than that which is removed bythe electrostatic filter.

In accordance with the instant invention, there is also provided avacuum cleaner comprising a dirty air inlet for receiving air containingdirt; a clean air outlet spaced for the dirty air inlet; an air flowpath extending downstream from the dirty air inlet to the clean airoutlet; and, a filtration assembly positioned in the air flow path, thefiltration assembly comprising a first cyclonic cleaning stage and asecond cyclonic cleaning stage downstream from the first cycloniccleaning stage; and, at least one electrostatic filter positioned in theair flow path downstream from the first cyclonic cleaning stage andupstream of the clean air outlet, wherein the electrostatic filter isremovable with the first cyclonic cleaning stage from the vacuum cleanerfor cleaning such as by washing with water.

In accordance with the instant invention, there is also provided avacuum cleaner for receiving and cleaning a dirty air stream to obtainclean air comprising first means for cyclonically treating the dirty airstream to obtain a partially cleaned air stream; and electrostaticprecipitation means positioned downstream from the first means forcyclonically treating a dirty air stream.

In one embodiment, the electrostatic precipitation means comprises meansfor generating a high voltage potential in response to air flow throughthe electrostatic precipitation means and conductive means fortransmitting the high voltage potential to dirt entrained in the dirtyair stream.

In another embodiment, the vacuum cleaner further comprises a batteryfor operating the vacuum cleaner and the electrostatic precipitationmeans produces a high voltage potential in response to air flow therethrough.

In another embodiment, the vacuum cleaner further comprises second meansfor further cyclonically treating the dirty air stream positioneddownstream from the first means for cyclonically treating a dirty airstream. The electrostatic precipitation means may be positioned in theair flow path downstream from the first means for cyclonically treatingthe dirty air stream and upstream of the second means for furthercyclonically treating the dirty air stream. Alternately, theelectrostatic precipitation means may be positioned in the air flow pathdownstream from the second means for further cyclonically treating thedirty air stream and upstream of the clean air outlet. The second meansfor further cyclonically treating the dirty air stream preferablyremoves particulate material larger than that which is removed by theelectrostatic precipitation means.

In another embodiment, the first means for cyclonically treating thedirty air stream is removably mounted in a housing and the electrostaticprecipitation means is removably mounted with the first means forcyclonically treating the dirty air stream.

In accordance with the instant invention, there is also provided avacuum cleaner for receiving and cleaning a dirty air stream to obtainclean air comprising first means for cyclonically treating the dirty airstream to obtain a partially cleaned air stream; second means forfurther cyclonically treating the dirty air stream; and, electrostaticfilter means positioned downstream from the first means for cyclonicallytreating a dirty air stream, wherein the second means for furthercyclonically treating the dirty air stream removes particulate materiallarger than that which is removed by the electrostatic filter means.

In accordance with the instant invention, there is also provided avacuum cleaner for receiving and cleaning a dirty air stream to obtainclean air comprising first means for cyclonically treating the dirty airstream to obtain a partially cleaned air stream; and, electrostaticfilter means positioned downstream from the first means for cyclonicallytreating a dirty air stream and removably mounted with the first meansfor cyclonically treating the dirty air stream.

In accordance with the instant invention, there is also provided amethod for filtering a dirty air stream in a vacuum cleaner to obtain aclean air stream comprising subjecting the dirty air stream to a firstcyclonic separation stage to obtain a partially cleaned air stream; and,subjecting the partially cleaned air stream to a second cyclonicseparation stage and an electronic filtration stage to obtain the cleanair stream.

In one embodiment, the method further comprises subjecting the partiallycleaned air stream to the second cyclonic separation stage to obtain atreated air stream and subjecting the treated air stream to theelectronic filtration stage to obtain the clean air stream.

In another embodiment, the method further comprises subjecting thepartially cleaned air stream to the electronic filtration stage toobtain a treated air stream and subjecting the treated air stream to thesecond cyclonic separation stage to obtain the clean air stream.

In another embodiment, the dirty air stream includes particulatematerial having various particle sizes and the second cyclonicseparation stage removes larger particles than those removed by theelectronic filtration stage.

In accordance with the instant invention, there is also provided anelectrostatic precipitator for separating chargeable particulate matterfrom a fluid stream comprising a housing having at least one fluid inletand at least one fluid outlet; at least one member movably positioned inthe housing for generating a high voltage potential in response to themovement of the at least one member in the housing; and, a conductivemember for transmitting the high voltage potential to particulate matterentrained in the fluid whereby particulate matter is oppositely chargedto the at least one member prior to encountering the at least one memberand is attracted to the at least one member during passage of thecharged particulate matter through the housing.

In one embodiment, the electrostatic precipitator further comprises adirecting member to cause the fluid to rotate the at least one member.

In another embodiment, the at least one member and at least a portion ofthe housing is constructed from a material that will produce a potentialdifference between the at least one member and the portion of thehousing due to frictional contact of the at least one member with thehousing as the at least one member moves in the housing due to the flowof fluid through the housing.

In accordance with the instant invention, there is also provided a nelectrostatic precipitator for separating chargeable particulate matterfrom a fluid stream comprising housing means having fluid inlet meansand fluid outlet means; individual chargeable means movably positionedin the housing means for generating a high voltage potential in responseto the movement of the individual chargeable means in the housing means;and, conductive means for transmitting the high voltage potential toparticulate matter entrained in the fluid whereby particulate matter isoppositely charged to the individual chargeable means prior toencountering the individual chargeable means and is attracted to theindividual chargeable means during passage of the charged particulatematter through the housing means.

In one embodiment, the electrostatic precipitator further comprises adirecting means to cause the fluid to rotate the individual chargeablemeans.

In another embodiment, the individual chargeable means and at least aportion of the housing means is constructed from a material that willproduce a potential difference between the individual chargeable meansand the portion of the housing means due to frictional contact of theindividual chargeable means with the housing means as the individualchargeable means moves in the housing means due to the flow of fluidthrough the housing means.

As will be appreciated, the electrostatic filter may comprise theportion of the filter assembly of the vacuum cleaner to remove thesmaller particles from the dirty air stream. For example, in a vacuumcleaner having first and second cyclonic separation stages, the firstcyclonic separation stage is preferably configured to remove thecoarsest particles from the air stream and the second cyclonicseparation stage is preferably configured to remove the smallestparticles from the air stream while the electrostatic filter is designedto remove particles having an intermediate size. Thus, if the secondcyclonic separation stage is positioned after the electrostatic filter,then the second cyclonic separation stage may be configured to removethe particles which are not filtered by either the first cyclonicseparation stage or the electrostatic filter. As the second cyclonicseparation stage need not be designed to remove the finest particulatematter, it may be of a lower efficiency then would otherwise by useableand accordingly may have a larger diameter. By increasing the diameterof second stage cyclones, the pressure drop across each second stagecyclone will be reduced thereby producing a further reduction in thepressure drop which occurs by the passage of air through the filterassembly of the vacuum cleaner and further reducing the power (size ofmotor) which is required.

If the electrostatic filter is positioned between the first and secondcyclonic separation stages, the finest particulate matter is removedprior to the second cyclonic separation stage treatment of the air. Theremoval of the fine particulate matter prior to this stage prevents thisparticulate matter from entering the second stage cyclones andcontaminating the interior surface of the second stage cyclones.

In a further alternate embodiment, the first and second cyclonicseparation stages may be positioned prior to the electrostatic filter.

In a further preferred embodiment, the electrostatic filter is removableso that it may be cleaned, such as by rinsing with water to remove theparticulate matter which is collected thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the instant invention will be more fullyand particularly understood in connection with the following descriptionof the preferred embodiments of the invention in which:

FIG. 1 is a cyclone separator as is known in the art;

FIG. 2 is a perspective view of a filter assembly for a vacuum cleaneraccording to the instant invention; and,

FIG. 3 is a perspective view of an alternate embodiment of the filterassembly for a vacuum cleaner according to the instant invention;

FIG. 4 is a perspective view of an upright vacuum cleaner according tothe instant invention;

FIG. 5 is a cross-section along line 5—5 in FIG. 4 of the vacuum cleanerof FIG. 4;

FIG. 6 is an enlargement of the upper portion of the cyclone chamberwhen positioned in the housing of the vacuum cleaner of FIG. 4;

FIG. 7 is an exploded view of the cyclone chamber and housing of thevacuum cleaner of FIG. 4;

FIG. 8 is a perspective view of the cyclone chamber when removed fromthe housing of the vacuum cleaner of FIG. 4;

FIG. 9 is an exploded view of the cyclone chamber of FIG. 8;

FIG. 10 is a perspective view of an electrostatic precipitator;

FIG. 11 is a cross-section along line 11—11 in FIG. 10 of theelectrostatic precipitator of FIG. 10; and,

FIG. 12 is a cross-section along line 12—12 in FIG. 10 of theelectrostatic precipitator of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The filter assembly of the instant invention may be used in conjunctionwith any vacuum cleaner. For example, the filter assembly may be usedfor an upright vacuum cleaner, a canister vacuum cleaner or a centralvacuum cleaner or the like. The dirty air stream which is processedusing the filter assembly described herein may be collected by, forexample, a wand or rotating brush positioned in the head of a vacuumcleaner as is known in the art. Such dirty air streams typicallycomprise dirt of varying particle sizes entrained in an air stream. Itwill be appreciated that the invention may also be used with a wet/dryvacuum cleaner.

The filter assembly may be used in conjunction with any design known inthe art. For example, as shown in FIGS. 2 and 3, the cyclone may be acylindrical cyclone having a dirty air feed conduit which is positionedexterior to cyclone bin 120. Alternately, as shown in FIGS. 4 and 5, thecyclone may be a cylindrical cyclone having a dirty air feed conduitwhich passes longitudinally through cyclone bin 120.

Referring to FIG. 2, the vacuum cleaner has a filter assembly 30comprising at least one first stage cyclone 32. First stage cyclone 32may, if desired, comprise a plurality of individual cyclones throughwhich the air passes either in sequence or in parallel. Preferably,filter assembly 30 uses only one first stage cyclone 32 as shown in FIG.2. Such a single cyclone may be designed to remove approximately 90% ormore, preferably at least 95% and most preferably at least 98% of theparticulate matter in the air stream entrained by the vacuum cleaner.

The dirty air may be introduced into first cyclone 32 by any means knownin the art. In the embodiment of FIG. 2, the dirty air is introducedtangentially into cyclone 32 by inlet 34. As shown in FIG. 2, cyclone 32may comprise a container or bin 120 having bottom 40 and side walls 38.It will be appreciated that container 120 may be of any particularconfiguration. As shown in the cross section of FIG. 2, container 120 iscylindrical in shape. Inlet 34 is in communication with the source ofdirty air via inlet conduit 42. Inlet conduit 42 may be of anyconfiguration known in the art which will convey the dirty air from asource (eg. a cleaning wand or the floor engaging head of a vacuumcleaner) to inlet 34. The dirty air travels around container 120 towardsbottom 40. At one point, the air travels upwardly adjacent the centralportion of container 120 to exit cyclone 32 by outlet 36. As shownherein, outlet 36 comprises an annular member which extends downwardlyinto the upper portion of cyclone 32 so as to prevent the partiallycleaned air travelling upwardly through outlet 36 from mixing with thedirty air introduced via inlet 34.

As shown in FIG. 2, the partially cleaned air exiting first stagecyclone 32 via outlet 36 is next passed through an electronic filter 50.Filter 50 may be positioned in air flow communication with outlet 36 inany manner. As shown in FIG. 2, filter 50 is held in position in the airflow path by upper and lower panels 52 and 54.

Container 120 is preferably removable from the vacuum cleaner by anymeans known in the art. When the container comprising bottom 40 andsidewalls 38 is positioned in the vacuum cleaner, it may abut againstlower panel 54 in sealing engagement so as to provide an air tightenclosure but for outlet 36.

The further cleaned air which exits electronic filter 50 passes throughoutlet 56 to a one or more second stage cyclones 60. The number ofsecond stage cyclones may vary depending upon, inter alia, the type ofparticulate matter which is to be filtered, the degree of separationwhich is required and the amount of pressure drop which is acceptablebased upon the motor which is provided to the vacuum cleaner. Secondcyclones 60 may also be of any particular design known in the art andmay be the same or different from first stage cyclone 32. Further, eachsecond stage cyclone 60 need not be the same.

As shown in FIG. 2, each cyclone 62 has an inlet port 58 for introducingair tangentially into the cyclone. Inlet port 58 may be of anyparticular construction. The air travels through cyclone 60 and dirtwhich is separated during the passage of air through cyclone 60 exitscyclone 60 via dirt outlet 64. This dirt may be collected in a dirtcollection chamber 66. The top of collection chamber 66 is provided byupper plate 68 which forms a seal with wall 62 of cyclone 60.Accordingly, chamber 66 may be defined by upper plate 68, upper panel 52and the wall of outlet 56. Collection chamber 66 may comprise an annularband extending around the interior of filter assembly 30. Alternately,it may extend only part way around the inner circumference of filterassembly 30 so that a single collection chamber 66 is provided for eachcyclone 60. The treated air exits cyclone 60 via outlet 70 which ispositioned at the upper end thereof. The treated air may be removed fromfilter assembly 30 via passage 72 which connects in flow communicationwith clean air outlet 74.

In the alternate embodiment shown in FIG. 3, filter 50 is positioneddownstream from second stage cyclones 60. According to this embodiment,the partially cleaned air exits first stage cyclone 32 via outlet 36 andtravels through outlet 56 to inlet 58 to second stage cyclones 60. Thetreated air exits second cyclone 60 via outlet 70. The treated air isthen fed to an electronic filter 50 via, for example, passages 72 whichcombine to form outlet 80 which is in communication with filter 50. Theclean air exits filter 50 and travels outwardly from the filter assembly30 via clean air outlet 74.

Clean air from clean air outlet 74 may be fed to a motor positionedabove clean air outlet 74 and, if desired, to further filtration means,such as additional cyclones (i.e. third stage cyclones), a HEPA™ filteror a further electrostatic filter.

In these embodiments, electronic filter 50 may be of any particularconstruction known in the art. Various constructions for electrostaticdevices which use charged regions to remove particulate matter from anair stream are known.

In a particular preferred embodiment, electronic filter 50 comprises anelectrostatic precipitator. The electrostatic filter is preferablydesigned to remove the smallest portion of the particulate matter fromthe air stream (eg. up to 30 microns). However, the actual level offiltration which may be achieved by the electrostatic filter will varydepending upon the design of filter 50.

FIGS. 4 and 5 demonstrate a known cyclone construction for an uprightvacuum cleaner as a further alternate embodiment. In this embodimentvacuum cleaner 100 has a floor cleaning head 102, means for movingcleaning head 102 across a floor (eg. wheels 104 which may comprise rearwheels or front and rear wheels), an upper body portion or housing 106rotatably attached to cleaning head 102, and a handle 108 for movingvacuum cleaner 100 across the floor. A dirty air flow conduit comprisingupstream portion 116 in cleaning head 102 and downstream portion incyclone bin 120 extends from opening 112 in sole plate 114 to inlet 34of cyclone 32. Upstream portion has an upstream end 124 positionedadjacent brush member 140 or the like and a downstream end 126.Downstream portion has an upstream end 128 and a downstream end 130. Avalve means 110 (eg. a rotatable valve as is known in the art) isprovided adjacent downstream end 126 in cleaning head 102 so as toconnect downstream portion 116 of the dirty air flow conduit in air flowcommunication with upstream portion 118 of the dirty air flow conduitwhen housing 106 is rotated rearwardly in the direction of arrow B inwhich position vacuum cleaner 100 is configured for use for cleaning afloor. In this embodiment, the cyclonic separator means uses one cyclone32 comprising cyclone bin 120.

Cyclone bin 120 has an air inlet 34, preferably at upper end 136thereof, adapted for providing an air flow tangentially to an inner dirtrotation surface or wall 38 of container 120. Air inlet conduit 138 mayalternately be configured to provide an axial flow of air to container120 and opening 34 at the downstream end of air inlet conduit 138 mayhave vanes to impart cyclonic flow to the air stream. Preferably, airinlet conduit 138 is configured to introduce the air tangentially tocontainer 120. As shown in FIGS. 5 and 8, air inlet conduit 138 includescurved portions for redirecting the air from an axial flow in downstreamportion 118 to a tangential flow at inlet 34. Air inlet conduit 138curves gently from downstream end 130 of downstream portion 118 so as totravel outwardly and generally radially towards inlet 34. Morepreferably, the change in direction of the dirty air from generallyvertical to generally horizontal and from generally horizontal togenerally tangential occurs so as to reduce the pressure drop during itstravel from downstream portion 118 to container 120.

Upstream and downstream portions 116 and 118 may comprise a singlemember (whether integrally formed or connected together to form acontinuous flow path) in which case a separated dirt collection meansmay be positioned below container 120. Alternately portions 116 and 118may be flexible so as to allow cyclone container 120 to be removed fromhousing 106 and emptied. In the preferred embodiment of FIGS. 4 and 5,upstream and downstream portions 116, 118 are separate elements anddownstream portion 118 is removable with container 120 from housing 106such that portions 116, 118 are in air flow communication when container120 is mounted in housing 106 of vacuum cleaner 100. Thus, if a blockagedevelops in the dirty air flow conduit, by removing container 120 fromhousing 106 as shown in FIG. 7, portions 116 and 118 may be individuallyaccessed at ends 126 and 128 to clean out the blockage. Preferably ends126 and 128 are substantially sealed together to prevent air and dirtleaking there from.

Preferably, downstream portion 118 and container 120 are a one pieceassembly so that when container 120 is removed from housing 106,downstream portion 118 is automatically removed at the same time. Thus,downstream portion 118 may be manufactured as part of container 120(such as by moulding it integrally therewith). Alternately, it may beseparately manufactured (such as by extrusion) and subsequently affixedto container 120 by any means known in the art (eg. by welding,engagement of male and female engagement members of the like).

In operation, the vacuum fan motor 122 is activated to induce an airflow through vacuum cleaner 100. The air flow causes a partial vacuum toform at end 124. Air, and entrained dirt, is drawn into upstream portion116, with the aid of brush member 140. The dirty air flow movesvertically in downstream portion 118 to opening 34 in air inlet conduit138 and is introduced tangentially to container 120. The airflow is thenaccelerated around wall 38 and proceeds generally downwardly along andaround wall 38 until it reaches a position towards bottom 40 ofcontainer 120, at which point the air flow travels upwardly through thecentral portion of cyclone container 120. Wall 142, an extension ofoutlet 36, may be provided in container 120. Wall 142 assists inpreventing the treated air travelling upwardly to outlet 36 from mixingwith the dirty air which is introduced into container 120 via inletconduit 138.

The removability of container 120 from housing 106 of vacuum cleaner 100is shown by reference to FIGS. 6-9. Housing 106 comprises a base 144, anupper portion 146 and struts 148 which extend between base 144 and upperportion of housing 146 so as to define a cavity within which container120 is received. It will be appreciated that housing 106 may be of anyconfiguration which provides an area in which bin 120 may be received.For example, it will be appreciated that if vacuum cleaner 100 is acanister vacuum cleaner, that container 120 may extend horizontally, orat any inclined angle to the horizontal and housing 106 may be of anyshape within which container 120 may be received.

Container 120 may be lockingly received in housing 106 by any meansknown in the art. In the preferred embodiment, container 120 is providedwith a lid 150 which has a recess 152 provided in handle 154 thereof.Container 120 and lid 150 comprise a cyclone chamber which is removablereceived in housing 106. Lower surface 156 of upper portion 146 ofhousing 106 is provided with a protrusion 158 which is receivable inrecess 152. By moving handle 154 downwardly to the position shown indotted outline in FIG. 6, protrusion 158 is removed from recess 152allowing bin 120 to be removed from base 144 as is shown in FIG. 7.Recess 152 and protrusion 158 are a male and female detent means. Itwill be appreciated that other male and female detent means or the likewhich are known in the art may be utilized so that container 120 may bereleasably lockingly received in housing 106.

The cleaned air travels upwardly out above container 120. Accordingly,lid 150 is provided with an upper surface 160. Cylindrical wall 142extends downwardly from upper surface 160. The intersection of uppersurface 160 and wall 142 describes opening 36 which is the clean airoutlet.

As can be seen in FIG. 8, downstream portion 118 of the dirty air supplyconduit is removed from housing 106 with container 120. Sealing means,such as O-ring 104 may be provided to join ends 126 and 128 in air flowcommunication when bin 120 is replaced in housing 106 so as to preventany leak or any substantial leak where ends 126 and 128 meet.

Lid 150 may be releasably mounted to container 120 by any means known inthe art. Referring to FIG. 9, lower end 164 of lid 150 is provided witha recessed surface 166 having two protrusions 168 provided therein.Upper end 170 of container 120 is provided with bayonet mounts 172 forreceiving protrusions 168. Accordingly, once container 120 is removedfrom housing 106, lid 150 is rotated slightly counter clockwise so as torelease the bayonet mount whereby lid 150 may then be lifted fromcontainer 120 thus allowing container 120 to be emptied.

Referring to FIGS. 10-12, a preferred embodiment for an electrostaticfilter is shown. In this embodiment, filter 50 is an electrostaticprecipitator. In accordance with the instant invention, filter 50preferably uses air flow and, more preferably, the air flow throughfilter 50 itself, to generate the electrostatic charge which is utilizedby filter 50.

As shown in FIGS. 10-12, filter 50 comprises a container 180 having aplurality of members 210 which rotate therein in response to the flowthrough chamber 180 of a fluid (eg. air). Accordingly, container 180 mayhave sidewalls 182, bottom 184 having upper surface 188 and lowersurface 190, and top 186 having upper surface 192 and lower surface 194.Top and bottom 184 and 186 may be of any particular configuration thatdefine end walls of container 180. It will be appreciated that whilesidewalls 182 are cylindrical as shown in FIG. 10, they may be of anyparticular shape provided that container 180 has a closed environmentfor the rotation of members 210. It will further be appreciated thatcontainer 180 must have at least one air inlet 196 and at least one airoutlet 202 so as to produce movement of members 210 in container 180.Preferably, container 180 has a plurality of air inlets 196 and airoutlets 202.

As shown in FIG. 10, air inlets 196 are provided in bottom 184 and airoutlets 202 are provided in top 186. It will be appreciated that theopenings for air inlets and air outlets 196 and 202 are preferably sizedso as not to permit the passage there through of members 210 and aresized and positioned to permit the effective movement of air incontainer 180 to move members 210 to produce a high voltage potential.

Members 210 and sidewalls 182 are constructed from any material whichwill generate the high voltage potential and transmit it to conductivelayer 204 due to the rotation (eg. cyclonic flow) of members 210 incontainer 180. Preferably, members 210 are made from styrofoam and walls182 are constructed from a plastic. The friction of styrofoam balls 210against one or more of sidewalls 182, bottom 184 and top 186 produce thehigh voltage potential. It will be appreciated that members 210 may beof any aerodynamic shape the will travel within container 180 to producefrictional engagement with the walls of container 180 due to the airflow there through.

Means is provided to cause members 210 to move within container 180 sothat a high voltage potential develops between members 210 and container180. Preferably, at least one of the air inlets 196, and preferably eachof the air inlets 196, are configured so as to cause the air tocirculate or rotate within container 180 and entrain members 210. Itwill be appreciated that directing vanes or the like may also beincluded with filter 50 (inside or outside container 180) so as to causethe air to circulate within container 180. The vanes, air inlets 196 orthe like define means which cause members 210 to move sufficientlywithin container 180 so as to develop a high voltage potential betweenmembers 210 and container 180. In the preferred embodiment of FIG. 10,air inlets 196 comprise a flange 198 which is angled with respect toupper surface 188 of bottom 184. Opening 200 is positioned beneathflange 198. As the air travels towards bottom 184, the air encountersflange 198 and is deflected to rotate within container 180 and entrainmembers 210.

A conductive layer 204 is provided for receiving and conducting the highvoltage potential to electrode means for imparting a corona discharge toparticles 212 which are entrained in the air stream travelling towardsfilter 50. Preferably, the electrode means is positioned upstream fromcontainer 180 so as to charge particles 212 prior to their entry intocontainer 180. Referring to FIG. 11, conductive layer 204, which may bea thin layer of a conductive metal, is provided on the exterior surfaceof sidewalls 182 by any means known in the art. Electrodes 208 areelectrically connected to conductive layer 204 by any means known in theart. Preferably, electrodes 208 are electrically connected to conductivelayer 204 by means of lower walls 206 to which conductive layer 204 isalso applied (see for example FIG. 12).

It will be appreciated that electrodes 208 may be of any configurationthat will produce a corona discharge so as to charge particles 212oppositely to the charge of styrofoam balls 210. As shown in FIG. 10,electrode 208 comprises an inward extension of lower walls 206 so as toimpinge on the air flow stream passing towards bottom 184. It will beappreciated that a plurality of electrodes extending transversely acrossthe airflow stream from one side of container 180 to the other may beutilized.

When particles 212 in the air stream come into proximity or in contactwith styrofoam balls 210, they are electrostatically attracted to eachother as they are oppositely charged. Thus, particles 212 are removedfrom the air stream and the treated air exits top 186 via outlets 202.

Container 180 may be positioned at any position in the dirty air flowpath of the vacuum cleaner. For example, as shown in FIG. 2, it may bepositioned downstream from first stage cyclone 32. Alternately, as shownin FIG. 3, it may be positioned downstream from second stage cyclone 60.Referring to FIG. 5, which uses only a single cyclone in the filtrationmeans 30 of vacuum cleaner 100, filter 50 is positioned in cylindricalwall 142 of outlet 36. Accordingly, when cyclone bin 120 is removed fromvacuum cleaner 100, filter 50 is automatically removed from vacuumcleaner 100 and is accessible for cleaning. If members 210 are made froma water resistant material (eg. styrofoam), filter 50 may be cleaned byplacing filter 50 under a stream of running water (eg. from a faucet).The water passing through filter 50 will remove particulate matter thatis electrostatically attracted to members 210. It will be appreciatedthat filter 50 may also be positioned in cavity 214.

Electrostatic filter 50 may be removably receivably mounted in outlet 36by any means known in the art. Referring to FIG. 5, wall 142 has angledflange members 216 provided on the inner surface thereof on whichelectrodes 208 are seated. A locking means, such as a hinged flap or adeformable flange 218 may be used to lockingly hold filter 50 inposition when the vacuum cleaner 100 is in operation. It will also beappreciated that a bayonet mount may be utilized. Outlets 202 may besized to receive a user's fingers in which case outlets 202 may alsofunction as a handle for filter 50. Alternately a handle may be providedon top 186.

In another embodiment, the vacuum cleaner may be powered by battery 220(see FIG. 5). In particular, it will be appreciated that by using theair flow to move members 210 within container 180, only a minimal amountof power is required to generate a high voltage potential thuspermitting the electrostatic precipitator 50 as shown in FIGS. 10-12 tobe included in a battery operated appliance.

It will be appreciated that the preferred embodiment of theelectrostatic precipitator 50 of FIGS. 10-12 may be used in otherapplications and need not be confined to use in a vacuum cleaner.

The cleaned air after passing motor 122 may then exit housing 106 viaoutlet 132 or it may first optionally pass through chamber 134, whichmay contain a further filtration means (eg. a HEPA™ filter) an a furtherelectrostatic filtration means.

It will be appreciated by those skilled in the art that variousadditions and modifications may be made to the instant invention and allof these are within scope of the following claims.

We claim:
 1. A vacuum cleaner comprising: (a) a dirty air inlet forreceiving air containing dirt; (b) a clean air outlet spaced for thedirty air inlet; (c) an air flow path extending downstream from thedirty air inlet to the clean air outlet; and, (d) a filtration assemblypositioned in the air flow path, the filtration assembly comprising: (i)at least one cyclonic cleaning stage in flow communication with thedirty air inlet and having a partially cleaned air outlet; and, (ii)atleast one electrostatic precipitator positioned in the air flow pathdownstream from the at least one cyclonic cleaning stage and upstream ofthe clean air outlet; and, (e) a battery for operating the vacuumcleaner including producing a high voltage potential which is used bythe electrostatic precipitator wherein the high voltage potential isproduced in response to air flow through the vacuum cleaner.
 2. Thevacuum cleaner as claimed in claim 1 wherein the at least one cycloniccleaning stage comprises at least a first cyclonic cleaning stage and asecond cyclonic cleaning stage downstream from the first cycloniccleaning stage.
 3. The vacuum cleaner as claimed in claim 2 wherein theat least one electrostatic precipitator is positioned in the air flowpath downstream from the second cyclonic cleaning stage and upstream ofthe clean air outlet.
 4. The vacuum cleaner as claimed in claim 2wherein the at least one electrostatic precipitator is positioned in theair flow path downstream from the first cyclonic cleaning stage andupstream of the second cyclonic cleaning stage.
 5. The vacuum cleaner asclaimed in claim 4 wherein the first cyclonic cleaning stage comprisesone cyclone and the second cyclonic cleaning stage consists of from twoto five second cyclones.
 6. The vacuum cleaner as claimed in claim 4wherein the second cyclonic cleaning stage removes particulate materiallarger than that which is removed by the at least one electrostaticprecipitator.
 7. The vacuum cleaner as claimed in claim 1 wherein the atleast one cyclonic cleaning stage comprises a cyclone chamber removablymounted in a housing and the at least one electrostatic precipitatorcomprises an electrostatic precipitator removably mounted in the cyclonechamber.
 8. The vacuum cleaner as claimed in claim 7 wherein the cyclonechamber has an air outlet and the electrostatic precipitator ispositioned in the air outlet of the cyclone chamber.
 9. The vacuumcleaner as claimed in claim 7 wherein the cyclone chamber has an airoutlet and the electrostatic precipitator is removably mounted in theair outlet of the cyclone chamber.
 10. A vacuum cleaner for receivingand cleaning a dirty air stream to obtain clean air comprising: (a)first means for cyclonically treating the dirty air stream to obtain apartially cleaned air stream; (b) electrostatic precipitation meansutilizing a high voltage potential and positioned downstream from thefirst means for cyclonically treating a dirty air stream; and, (c) abattery providing essentially the sole source of power for operating thevacuum cleaner and generating the high voltage potential in response toair flow through the vacuum cleaner.
 11. The vacuum cleaner as claimedin claim 10 further comprising second means for further cyclonicallytreating the dirty air stream positioned downstream from the first meansfor cyclonically treating a dirty air stream.
 12. The vacuum cleaner asclaimed in claim 11 wherein the electrostatic precipitation means ispositioned in the air flow path downstream from the first means forcyclonically treating the dirty air stream and upstream of the secondmeans for further cyclonically treating the dirty air stream.
 13. Thevacuum cleaner as claimed in claim 11 wherein the electrostaticprecipitation means is positioned in the air flow path downstream fromthe second means for further cyclonically treating the dirty air streamand upstream of the clean air outlet.
 14. The vacuum cleaner as claimedin claim 11 wherein the second means for further cyclonically treatingthe dirty air stream removes particulate material larger than that whichis removed by the electrostatic precipitation means.
 15. The vacuumcleaner as claimed in claim 10 wherein the first means for cyclonicallytreating the dirty air stream is removably mounted in a housing and theelectrostatic precipitation means is removably mounted with the firstmeans for cyclonically treating the dirty air stream.
 16. A vacuumcleaner for receiving and cleaning a dirty air stream to obtain cleanair comprising: (a) first means for cyclonically treating the dirty airstream to obtain a partially cleaned air stream; (b) an electrostaticfilter positioned downstream from the first means for cyclonicallytreating a dirty air stream; and, (c) a battery for operating the vacuumcleaner and providing essentially the sole source of power fordeveloping charge for the electrostatic filter.
 17. The vacuum cleaneras claimed in claim 16 further comprising second means for furthercyclonically treating the dirty air stream positioned downstream fromthe first means for cyclonically treating a dirty air stream.
 18. Thevacuum cleaner as claimed in claim 17 wherein the electrostatic filteris positioned in the air flow path downstream from the first means forcyclonically treating the dirty air stream and upstream of the secondmeans for further cyclonically treating the dirty air stream.
 19. Thevacuum cleaner as claimed in claim 17 wherein the electrostatic filteris positioned in the air flow path downstream from the second means forfurther cyclonically treating the dirty air stream and upstream of theclean air outlet.
 20. The vacuum cleaner as claimed in claim 17 whereinthe second means for further cyclonically treating the dirty air streamremoves particulate material larger than that which is removed by theelectrostatic filter.